OP...
Document everything she says and does to you and others. Get together with other coworkers and crested a document where all of you sign it, then get it notarized.
That way, should something go down, you and your co-workers have paperwork to protect you.
Based on what little you shared, I have a feeling those in upper management know about it and is low key trying to protect her.
Just an idea for ya...
Holy shyt, this!
People like this are POISON.
They know any way to take away negative attention from themselves is to put down others and act like they are better. They can't focus on their own work, so they cheat their way up and use slander for their own gain.
Keep focusing on your job. Report her for slander and instigating. Get witnesses too. Have two copies for HR/Union Rep and yourself. She doesn't want you to move ahead in the company.
Goddamn thats a lot of work. How do you do it?

